peteroznewman
posted this
13 September 2018
- Last edited 13 September 2018

Jon,

That was a great blog about Remote objects that Sandeep mentioned in his post.

You ask about the pros and cons of Displacement vs. Remote Displacement.

Displacement doesn't add any extra equations to the model, it actually removes some equations from the model, so that might have some small effect on solution time compared with Remote Displacement. Maybe Displacement allows the model to converge more reliably than a Remote Displacement. If you are doing just displacement, then a Displacement Support is generally going to be better than a Remote Displacement.

Joint - Displacement requires a joint, while Remote Displacement doesn't. A joint can define a relationship between two bodies (face or edge) or between a body and ground, while a Remote Displacement is only to ground.

By the definition, "A Remote Displacement enables you to apply both displacements and rotations at an arbitrary remote location in space". What I don't understand properly is what example can there be, in which we apply displacement at a remote location?

So, when the relationship is between a body and ground, using Remote Displacement will give same results as using Joint-Displacement?

peteroznewman
posted this
18 September 2018
- Last edited 19 September 2018

Hello Jon,

An example of when I would use a remote displacement is where I have an 800 mm long cantilevered structure (bracket) that carries a load at the tip and has a base bolted to a wall. I define plasticity for the metal of the structure and I want to plot the force-displacement curve to determine the ultimate load capacity of the bracket for a load at the tip. It is generally best to apply displacements to generate a force-displacement plot when you want the force to reach a maximum and then continue plotting lower forces as the bracket fails.

The bracket design is such that no high stress occurs along the most of the length of the 800 mm, all the high stress is less than 100 mm away from the wall. I could mesh the whole structure and apply a 300 mm displacement to the tip and that would give me a result. Maybe the mesh has 80,000 nodes and takes 80 minutes to pull the tip down 300 mm.

Or, I could go into geometry and cut 600 mm off the structure and just leave 200 mm from the wall on out. Now I still want to pull the tip down 300 mm, but the tip is gone. That is where a remote displacement comes in. I can put the coordinates of the remote point 800 mm off the wall, and scope it to the cut face that is 200 mm off the wall. The mesh on this model may only have 20,000 nodes and take 20 minutes to pull the remote point down 300 mm. Since all the plastic deformation is happening in the first 100 mm from the wall, the ultimate load calculated from the maximum value of the force-deflection plot is the same as above, but I saved 60 minutes compared with the full model solution.

A remote displacement and a joint to ground may create the same code, under-the-hood. They seem to be equivalent to me.